Apparatus for generating and delivering combustion gases and reduction gases to a blast furnace

ABSTRACT

Described are two bustle pipes encircling blast furnace, one for receiving combustion blast gas under pressure and one for receiving reducing gas. Tuyeres lead from the combustion gas bustle pipe to the interior of the combustion zone of the furnace while other tuyeres lead from the reducing gas bustle pipe to the interior of the furnace immediately below its reduction zone. A gas turbine engine generates and supplies combustion blast gas made up of O2, CO2, H2O and N2 to the combustion gas bustle pipe through a duct for delivery to the combustion zone of the furnace. Part of the gas generated by the turbine engine is passed through an afterburner in the duct to raise the temperature of the gas and use up all of the excess O2 in the gas and form CO2 and H2O in the process thus transforming the gas into a superheated reducing gas made up of CO2, H2O and N2. Both gases pass through a heat exchanger prior to being delivered to the respective bustle pipes whereby the temperature of the combustion blast gas is raised and the reducing gas temperature is lowered. If desired, an oxygen gas inlet may be provided on the duct portion carrying the combustion blast gas so that oxgyen gas may be injected into the combustion blast gas just prior to its introduction into the combustion gas bustle pipe.

v [75] Inventor:

Ilnited States Patent [191 Stevens APPARATUS FOR GENERATING AND DELIVERING COMBUSTION GASES AND REDUCTION GASES TO A BLAST FURNACE John H. Stevens, Peters Township, Washington County, Pa.

[73] Assignee: United States Steel Corporation, Pittsburgh, Pa.

[22] Filed: Sept. 11, 1972 [21] Appl. No.: 287,938

Primary Examiner-Gerald A. Dost Attorney-Donald S. Ferito [57] ABSTRACT Described are two bustle pipes encircling blast fur- Dec. 11, 1973 nace, one for receiving combustion blast gas under pressure and one for receiving reducing gas. Tuyeres lead from the combustion gas bustle pipe to the interior of the combustion zone of the furnace while other tuyeres lead from the reducing gas bustle pipe to the interior of the furnace immediately below its reduction zone. A gas turbine engine generates and supplies combustion blast gas made up of 0 C0 11 0 and N to the combustion gas bustle pipe through a duct for delivery to the combustion zone of the furnace. Part of the gas generated by the turbine engine is passed through an afterburner in the duct to raise the temperature of the gas and use up all of the excess 0 in the gas and form CO and H 0 in the process thus transforming the gas into a superheated reducing gas made up of CO H 0 and N Both gases pass through a heat exchanger prior to being delivered to the respective bustle pipes whereby the temperature of the combustion blast gas is raised and the reducing gas temperature is lowered. If desired, an oxygen gas inlet may be provided on the duct portion carrying the combustion blast gas so that oxgyen gas may be injected into the combustion blast gas just prior to its introduction into the combustion gas bustle pipe.

2 Claims, 1 Drawing Figure MEL TING ZUIVE APPARATUS FOR GENERATING AND DELIVERING COMBUSTION GASES AND REDUCTION GASES TO A BLAST FURNACE The present invention relates generally to blast furnaces and more particularly to improved apparatus for generating and supplying hot combustion blast gas and reducing gas under pressure to a blast furnace.

lt is a primary object of my invention to provide apparatus utilizing a gas turbine engine in the form of an aircraft jet engine including a compressor, combustion chamber and turbine to supply hot combustion gas and reducing gas to ablast furnace. A duct connects the exhaust end of the turbine with two bustle pipes surrounding the blast furnace and connected with the interior thereof by means of tuyeres for receiving heated combustion blast gas and reducing gas, respectively, for delivery to the combustion and reduction zones of the furnace, respectively. The apparatus further includes an afterburner in the duct through which some of the gas issuing from the turbine is passed to transform it into superheated reducing gas, and a heat exchanger in the duct through which combustion blast gas received directly from the turbine as well as the superheated reducing gas pass prior to their introduction into their respective bustle pipes for delivery into the furnace. Passage of the gases through the heat exchanger raises the temperature of the combustion blast gas and lowers the temperature of the reducing gas.

The most pertinent references of which I am aware are US. Pat. No. 3,216,711 and No. 3,216,712, both dated Nov. 9, 1965.

The above and other objects will become more apparent after referring to the following specification and attached drawing, in which:

The single FIGURE of the drawing is an elevational view partly in section of the apparatus of the invention.

Referring more particularly to the drawing, reference character 2 designates generally a blast furnace provided with the apparatus of my invention.

An aircraft-type jet engine 4 including acompressor 6, combustion chamber 8, and turbine functions as the power and gas source for blowing the blast furnace 2, thus eliminating the need for conventional stoves. The jet or gas turbine engine 4 may be of the same type as the Pratt and Whitney JT3 aircraft jet engine.

A duct 12 is connected with the exhaust end of the turbine 10 and includes two gas passageways l4 and 16 connected with bustle pipes 18 and 20, respectively, which encircle the furnace 2. Bustle pipes 18 and20 are connected with the interior of the furnace by means of tuyeres 22 and 24, respectivelyrBustle pipe 18 receives hot combustion blast gas from the turbine 10 through the passageway 14 while bustle pipe 20 receives superheated reducing gas from turbine 10 through passageway 16. The combustion blast gas is introduced by tuyeres 22 into the combustion zone of the furnace and the superheated reducing gas is introduced into the interior of the furnace by tuyeres 24 immediately below the reduction zone.

A control valve 26 diverts the exhaust gas issuing from the turbine 10 partially into the passageway 14 and partially into passageway 16. The temperature of the gas delivered into passageway 14 from turbine 10 is raised by passage through a heat exchanger 28 before it enters the bustle pipe 18, as will be more fully explained hereinafter. This gas is made up of 0 CO H 0, and N as it enters bustle pipe 18 and is the combustion blast gas for furnace 2.

An afterburner 30 is provided in passageway 16 through which the gas diverted to passageway 16 by valve 26 passes and is thereby elevated in temperature to approximately 4,000F. The afterburner 30 burns sufficient natural gas or fuel oil to use up all of the excess O in the gas issuing from turbine 10, forming CO and H 0 in the process. The heat exchanger 28 is disposed in the duct 12 in the path of the gases flowing through passageway 14 between the control valve 26 and the bustle pipe 18 and in the path of the gas flowing through passageway 16 between the afterburner 30 and bustle pipe 20. As the gas passes through the heat exchanger 28, the heat exchanger transfers heat from the superheated gases flowing from the afterburner to the combustion gases flowing through the passageway 14. Accordingly, the sensible heat of the combustion gas blast is raised while that of the reducing gas is lowered. Gases in the combustion and melting zone of the furnace must have a temperature higher than the melting point of iron which is approximately 2,800F. Higher combustion and melting zone temperatures are sustained with the injection of high temperature combustion blast gas into the furnace at the combustion zone by means of the tuyeres 22 attached to bustle pipe 18. By injecting the reducing gas into the furnace, just below the reduction zone thereof, through tuyeres 24 attached to bustle pipe 20, the endothermic reaction of CO and H 0 combining with carbon inside the furnace form CO and H which absorbs a large amount of the sensible heat of the gases rising from the combustion zone of the furnace. Reducing gases CO and H formed by the above reactions result in the achievement of greater efficiency in the reduction of iron oxides and thus increase the production rate of blast furnace.

Additional amounts of 0 may be injected through an inlet attached to the duct 12 leading to passageway 14 just before its connection with bustle pipe 18 to increase the flame temperature in the combustion zone of the furnace.

While I have shown but one embodiment of my invention, other adaptations and modifications may be made without departing from the scope of the following claims.

I claim: 1. In a blast furnace having a hearth, a combustion zone above said hearth, a melting zone above said combustion zone and a reduction zone above said melting zone the improvement therewith of apparatus for generating and delivering combustion gas and reducing gas to said blast furnace, said apparatus comprising a first bustle pipe encircling said furnace and having an inlet for receiving combustion gas under pressure, tuyeres leading from said first bustle pipe to the interior of said combustion zone, a second bustle pipe encircling said furnace spaced from said first bustle pipe and having an inlet for receiving reducing gases under pressure, tuyeres leading from said second bustle pipe to the interior of said blast furnace immediately below the reduction zone thereof, a gas turbine engine including a compressor, combustion chamber, and a turbine arranged in tandem, and an exhaust duct leading from the discharge end of said turbine, said duct having a first passageway leading to and connected with said inlet in said first bustle pipe and a second passageway leading to and connected with said inlet in said second bustle second bustle pipe is reduced and the temperature of the gas passing through said first passageway to said first bustle pipe is raised.

2. Apparatus as defined by claim 1 including an inlet tube in said first passageway disposed between said heat exchanger and said first bustle pipe for introducing supplemental oxidizing gas into the gas flowing into said first bustle pipe from said first passageway to raise the temperature in the combustion zone of said fur- 

2. Apparatus as defined by claim 1 including an inlet tube in said first passageway disposed between said heat exchanger and said first bustle pipe for introducing supplemental oxidizing gas into the gas flowing into said first bustle pipe from said first passageway to raise the temperature in the combustion zone of said furnace. 